Definitions of blemish:

• noun:   a mark or flaw that spoils the appearance of something (especially on a person's body)

  Example: "A facial blemish"

• verb:   mar or impair with a flaw

  Example: "Her face was blemished"

• verb:   add a flaw or blemish to; make imperfect or defective
• verb:   mar or spoil the appearance of